Cycloauration of pyridyl sulfonamides

The pyridyl-2-alkylsulfonamides C(5)H(4)N(CH(2))(n)NHSO(2)R (n = 1,2; R = Me, Ph or p-C(6)H(4)Me) and 8-(p-tosylamino)quinoline undergo facile cycloauration reactions with H[AuCl(4)] in water, giving metallacyclic complexes coordinated through the pyridyl (or quinolyl) nitrogen atom and the deprotonated nitrogen of the sulfonamide group. The complexes have been fully characterised by NMR spectroscopy, ESI mass spectrometry and elemental analysis. The X-ray crystal structures of two derivatives reveal the presence of non-planar sulfonamide nitrogen atoms. The complexes show low activity against P388 murine leukaemia cells, possibly as a result of their ease of reduction with mild reducing agents.     

Palladium(II) complexes of readily functionalized bidentate 2-pyridyl-1,2,3-triazole "click" ligands: a synthetic, structural, spectroscopic, and computational study

The Cu(I)-catalyzed 1,3-cycloaddition of organic azides with terminal alkynes, the CuAAC "click" reaction is currently receiving considerable attention as a mild, modular method for the generation of functionalized ligand scaffolds. Herein we show that mild one-pot "click" methods can be used to readily and rapidly synthesize a family of functionalized bidentate 2-pyridyl-1,2,3-triazole ligands, containing electrochemically, photochemically, and biologically active functional groups in good to excellent yields (47-94%). The new ligands have been fully characterized by elemental analysis, HR-ESI-MS, IR, (1)H and (13)C NMR and in three cases by X-ray crystallography. Furthermore we have demonstrated that this family of functionalized "click" ligands readily form bis-bidentate Pd(II) complexes. Solution studies, X-ray crystallography, and density functional theory (DFT) calculations indicate that the Pd(II) complexes formed with the 2-(1-R-1H-1,2,3-triazol-4-yl)pyridine series of ligands are more stable than those formed with the [4-R-1H-1,2,3-triazol-1-yl)methyl]pyridine "click" ligands.     

Synthesis,characterisation and biological activity of cycloaurated organogold(III) complexes with imidate ligands

The reactions of the cycloaurated gold(III) complexes (2-bp)AuCl₂ (2-bp = 2-benzylpyridyl) or (damp)AuCl₂ (damp = Me₂NCH₂C₆H₄) with an excess of sodium saccharinate (Nasacc), potassium phthalimidate (Kphth), or with isatin and trimethylamine in refluxing methanol results in the successful isolation of a series of new gold(III) imidate complexes. These were characterised by NMR and IR spectroscopies, and by X-ray structure determinations on (2-bp)Au(sacc)₂ and (2-bp)Au(phth)₂. In both structures, the planes of the saccharinate and the phthalimidate ligands are orientated almost perpendicular to the gold coordination plane. As expected from trans-influence considerations, the Au–N_(imidate) bond lengths trans to the aryl carbon atoms are longer than the Au–N_(imidate) bond lengths trans to the pyridyl groups. The complexes have also been characterised by electrospray ionisation MS; in the presence of halide ligands, one imidate ligand is readily displaced. Anti-tumour (P388 murine leukemia) and selected anti-microbial data for the new complexes are reported. Surprisingly, all three damp complexes had low anti-tumour activity, which is likely to be a consequence of the poor solubility of these complexes. The synthesis and characterisation of a related gold(III) bis(amidate) complex derived from sulfathiazole is also described.     

Excitation ahead of shock fronts in krypton measured by single line laser absorption

The number densities of the metastable 5s[1 1/2]2 state and the 5s[1 1/2]1 state of krypton ahead of shock fronts have been determined from the measured absorption of single line laser radiation. Shocks with Mach numbers from 12 to 21 were investigated at preshock pressures from 0.7 to 2.7 kPa. An exponential rise of this excitation precursor having time constants of about 8 ws is found. The metastable concentration atM = 20 is about 10 ppm. The experimental results agree within an order of magnitude with published model predictions for argon and xenon shocks.     

Organogold(III) complexes containing chelating bis(amidate) ligands: Synthesis,characterisation and biological activity

Reactions of cycloaurated gold(III) dichloride complexes, with 1,2-C₆H₄(NHCOMe)₂ and silver(I) oxide, or with C₂H₄(NHSO₂Tol)₂ (Tol = p-tolyl) or 1,2-C₆H₄(NHSO₂Tol)₂ and trimethylamine, give a series of new auracyclic complexes containing the Au–NR–CH₂CH₂–NR (R = SO₂Tol) and Au–NR–C₆H₄–NR (R = COMe or SO₂Tol) five-membered ring systems. An X-ray structure determination on (2-bp)Au{N(COMe)C₆H₄N(COMe)} (2-bp = cycloaurated 2-benzylpyridine) shows the presence of puckered metallacyclic rings, with both acetyl substituents positioned below the Au(III) coordination plane. The complex (2-bp)Au{N(COMe)C₆H₄N(COMe)} undergoes ring cleavage in the presence of halide and water, to give the complex (2-bp)Au{N(COMe)C₆H₄NH(COMe)}Cl, which was characterised crystallographically, and shown to contain a monodentate amidate ligand. Biological activity studies of the new auracyclic complexes are also reported, against P388 murine leukaemia cells and a range of bacteria and fungi, with a number of complexes showing high activity.     

Catalytic activity of cycloaurated complexes in the addition of 2‐methylfuran to methyl vinyl ketone

Cycloaurated gold(III) complexes derived from cycloaurated iminophosphorane, triphenylphosphine sulfide or selenide, or pyridylsulfonamide ligands have been assessed for their catalytic activity in the addition of 2‐methylfuran to methyl vinyl ketone. Addition of AgBF₄ was generally needed for high activity, although those with coordinated atoms of high trans influence showed some activity in the absence of added Ag⁺. Copyright © 2011 John Wiley & Sons, Ltd.     

Toward the self-assembly of metal-organic nanotubes using metal-metal and π-stacking interactions: bis(pyridylethynyl) silver(I) metallo-macrocycles and coordination polymers

Shape-persistent macrocycles and planar organometallic complexes are beginning to show considerable promise as building blocks for the self-assembly of a variety of supramolecular materials including nanofibers, nanowires, and liquid crystals. Here we report the synthesis and characterization of a family of planar di- and tri-silver(I) containing metallo-macrocycles designed to self-assemble into novel metal-organic nanotubes through a combination of π-stacking and metal-metal interactions. The silver(I) complexes have been fully characterized by elemental analysis, high resolution electrospray ionization mass spectrometry (HR-ESI-MS), IR, (1)H and (13)C NMR spectroscopy, and the solution data are consistent with the formation of the metallo-macrocycles. Four of the complexes have been structurally characterized using X-ray crystallography. However, only the di-silver(I) complex formed with 1,3-bis(pyridin-3-ylethynyl)benzene is found to maintain its macrocyclic structure in the solid state. The di-silver(I) shape-persistent macrocycle assembles into a nanoporous chicken-wire like structure, and ClO(4)(-) anions and disordered H(2)O molecules fill the pores. The silver(I) complexes of 2,6-bis(pyridin-3-ylethynyl)pyridine and 1,4-di(3-pyridyl)buta-1,3-diyne ring-open and crystallize as non-porous coordination polymers.     

(p-Cymene)thioglycollatoruthenium(II) dimer; a complex with an ambi-basic S,O-donor ligand

The title compound was prepared from the (p-cymene)ruthenium chloride dimer and thioglycollic acid. The structure is a centrosymmetric dimer bridged by the soft-base S atoms, with the hard-base O atoms of the carboxylate group chelating to form a five-membered twisted-ring. The coordination of the ruthenium atoms is completed by a η⁶-p-cymene ligand, giving an 18-electron count. The Ru–S bonds are essentially equal at 2.396(1) Å.     

Palladium(II) and platinum(II) complexes of bidentate 2-pyridyl-1,2,3-triazole “click” ligands: Synthesis,properties and X-ray structures

The synthesis and characterization of palladium(II) and platinum(II) complexes of isomeric bidentate 2-pyridyl-1,2,3-triazole “click” ligands is reported. The complexes have been fully characterized by elemental analysis, HRESI-MS, IR, UV–Vis, ¹H and ¹³C NMR spectroscopy. Additionally, the molecular structures of the Pd(II) and Pt(II) complexes of the 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine ligand are confirmed by X-ray crystallography. Solution studies indicate the 2-(1-benzyl-1H-1,2,3-triazol-4-yl)pyridine ligand forms more stable complexes with Pd(II) and Pt(II) than the isomeric 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine ligand.